Is it necessary to have the check valve in the vacuum line? If so can any valve work or do I need to order one from parts supplier and pay more shipping than the part costs. How much vacuum is needed off the vacuum port? Can't find how much in any books . :confused:

I don't think the '68 came with the check valve and the hose routing was very close to the 69's. The only problem you will have without it is, any leak in the many feet of vacuum line and the 20 something connections will directly effect the way the engine runs. The check valve protects the engine from the headlight system... I found my RS system retains about 10" of vacuum with the engine off...

Can I replace with any check valve from auto parts store? Want to go electric conversion but I am too cheap for the $550.00

Not sure, if it allows vacuum to pull in one direction but restricts it in the other it may work... What have you seen at the parts store? something on the "Help" shelf maybe? It's only a $5 item why not just order one from Ground Up or Year One?